Satisfying the world's energy needs is a demanding endeavor. Presently, fossil fuels are responsible for supplying the bulk of these worldwide needs. However, fossil fuel supplies are finite, their consumption often has adverse environmental effects, their cost widely variable and somewhat unpredictable, and independence from them is long considered to be politically advantageous.
Alternative energy sources are being actively sought and developed. Solar and wind energy are attractive alternatives to fossil fuels. Wind farms have been developed and energy from them complements conventional energy supply. The promise of efficient and cost effective solar energy has yet to be realized, although considered to be a future solution to the worldwide energy problem.
Solar radiation, at its maximum produces about 1000 Watts/m2. Solar cells can operate up to 30% efficiency, but typical values of efficiency for the most economical units are about 15-20%. Hence, typical output is about 200 Watts/m2, or about 20,000 μW/cm2 at full solar radiation. Under more typical lighting conditions, the output would be an order of magnitude lower, about 2,000 μW/cm2. Typical photovoltaic output value is about 12,000 μW/cm2 at full sun at the equator during the vernal equinox at midday, which is the absolute peak. More typical values, but still under bright conditions, would be an order of magnitude lower, perhaps 1,200 μW/cm2. The benchmark for commercial photovoltaic cells in fairly bright light is from about 1,000 to about 2,000 μW/cm2.
Despite the advances made in harnessing energy from the sun, a need exists to develop solar energy systems that provide electrical energy in an efficient and cost effective manner. The present invention seeks to fulfill this need and to provide further related advantages.